Cable connector



June 28, 1960 M. SKUNDA CABLE CONNECTOR Filed Dec. 12, 1956 A TTOP/Vfy United States .PatentfO 2,943,139 CABLECONNECTOR Filed Dec. 12, 19-56, Ser. No. 627,912

1 Claim. c1. ru -r1 This invention relates to an improved cable connector and more particularly to a combined cable connector and sealing boot adapted to cooperate with igniter elements of the recessed type to increase resistance to flashover.

An ever-present problem in the design of ignition systems is that of preventing electrical flashover between the cable connector and the igniter shell which normally acts as the ground electrode. A common expedient used in the past for increasing resistance to fiashover is that of forming the igniter with a recessed type centerwire, that is, with the terminal end of the centerwire recessed within the axial bore of the insulator to provide a well in which the ignition cable is positioned for electrical connection wtih the centerwire, thus increasing the flashover path from the end of the cable to the ground electrode. In order to provide a connection sealed against moisture and other short-circuiting contaminants, an annular groove or bead is provided on the inner surface of the insulator defining the well for cooperation with a correspondingly formed head or groove on the cable. Such construction presents serious difficulties from a production standpoint since the formation of a groove or bead in the centerbore of an insulator is extremely difficult and expensive and since the cable has to be formed with greater precision.

Accordingly, it is an object of my invention to provide a readily removable cable connector of simple and inexpensive design adapted to form a contaminant sealed electrical connection with a recessed type spark plug.

It is a further object of my invention to provide a cable connector adapted to form an electrical connection with a recessed type plug wherein a moisture proof seal is formed with the outer surface of the plug. It is a still further object of my invention to provide a cable connector adapted to form a sealed connection with a recessed type plug wherein pressure imposed on the connector from the insulator centerbore tendsto improve the seal.

These and other objects of my invention are achieved by providing a cable connector of elongate design adapted to be positioned within the insulator centerbore and having means provided thereon between its ends adapted to be positioned over the outer surface of the plug insulator and form a sealed connection therewith.

The objects of my invention will be apparent from the following description having reference to the accompanying drawing in which Figure l is a view in section of a straight cable connector formed in accordance with my invention and assembled with a ribbed type spark plug, and Figure 2 is a similar but fragmentary view of an angle type modification of the cable connector formed in accordance with my invention.

Referring now to the drawing and more particularly to Figure 1, there is shown a spark plug 1 comprising a shell 3 adapted to function as the ground electrode and an insulator subassembly 5. Insulator subassembly 5 comprises an insulator 7 having a centerbore 9 in which there is positioned a centerwire assembly comprising a 2,943,139 latented June 28', 1960 2 center electrode '11 having electrical contact with a terminal screw '13 through a conductive glass seal ma- 'terial 15 which is well known in the art and form no part of my invention. As is clearly shownin'Figures 1 and 2, the terminal end of the centerwire assembly, terin'in'al screw '13, is recessed within centerbore "9 *thus "forming -a spark plug "of the recessed type.

iks is clearly shown i'n Figure -'1,-an ignition cable 17 is placed in electrical contact with terminal screw "13 by means of cable connector 19. In accordance with my invention, connector 19 is formed with a generally elongate body portion 21 adapted to be connected at its inner end with the ignition cable 17 and at its outer end with the terminal screw 13, a conductor wire 23 being secured to and electrically connecting the contacts at each end. As shown, the contact at the inner end consists of a wood screw 25 while that at the outer end consists of a contact spring 27. While any well known contact member may be used at either end, I prefer to use a compression type member at the outer end such as spring contact 27 for reasons hereinafter set forth.

As is clearly shown in Figures 1 and 2, the wall of the centerbore 9 is formed without grooves or beads and the portion of the connector body 21 extending into the bore is in spaced relationship with the bore. A seal between the connector 19 and the insulator 7 is obtained by providing a sealing member 29 intermediate the ends of the connector which member is adapted to form a sealing connection with the outer surface of the insulator 7. As shown, member 29 is generally cup-shaped with the open end facing the outer end of the connector 19. An annular head 31 is formed on the inner Wall surface of the member 29 and adjacent its open end, the bead being so dimensioned as to snap into locking means or a groove formed between adjacent ribs 33 on the insulator 7 to form a moisture proof seal therewith.

It should be noted that the pressure exerted by the contact spring 27 acts to form a tighter seal between the member 29 and the insulator 7. Similarly, it should be noted that any tendency for gas leakage from about the centerwire assembly also tends to form a better seal between member 29 and the insulator 7, thus tending to prevent failure of the plug due to gas leakage. Connector 19 may be formed of any tough, flexible material such as polyethylene, Teflon-a tetrafiuoroethylene polymer, nylon-the polymerization product of a hexamethylenedia-mine salt of adipic acid, and the like.

The connector 19 may be assembled on the insulator 7 by inserting the outer end into the centerbore and positioning one side of the insulator within member 29 and progressively causing the other side to advance therein until the head 31 snaps into the groove between ribs 33. As is shown in Figures 1 and 2, sealing member 29 is provided with a flange-like extension 35 which serves as a gripping lever to facilitate removal of the connector from the plug 1.

The modification shown in Figure 2 is the same as that in Figure 1 except that the body 21 is angularly formed instead of being substantially straight.

While the form of the embodiment of my invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted as may come within the scope of the claim which follows.

What is claimed is:

In combination, a recessed type spark plug comprising a shell, an insulator subassembly within said shell, said subassembly comprising a center electrode within an insulator, a connector assembled with said insulator subassembly comprising an elongated body member, an electrical contact at the inner end of said body member adapted to be connected to a power cable, a compression spring type contact at the outer end of said body member electrically connected to the terminal end of said center v electrode, an electrical conductor connecting said contacts, a generally cup-shaped member formed on said body member between its ends and positioned about the end and outer surface of saidinsulator, the outer end of 5 said body member being positioned .within the centerbore of said insulator, an annular groove formed on the outer surface of said insulator, and an annular bead formed on the inner surface of said cup-shaped member, 1 said annular groove and said bead cooperating to form 10 a sealed connection, said compression type contact serving to urge said bead into sealing connection with said annular groove. I

References Cited in the file of this patent UNITED STATES PATENTS Keath Dec. 22, Rose Dec. 19, Candelise Mar. 18, Holton Mar. 15, Lucas Aug. 16, Kirk Feb. 19, Colbert May 20,

FOREIGN PATENTS Australia Apr. 21,

France June 9, 

